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    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #box1{width: 200px;height: 200px;background: chartreuse; border-radius: 20px;} 
        #box2{width: 200px;height: 200px;background: rgb(226, 37, 100); 
        border-radius: 100px;}
        #box3{width: 300px;height: 300px;background: rgb(17, 230, 166); 
        border-radius: 10px 30px 50px  150px;}
        #box4{width: 200px;height: 200px;background: rgba(221, 218, 15, 0.808); border-radius: 20px/50px;}
        #box5{width: 200px;height: 100px;background: rgba(8, 12, 224, 0.822);
        border-radius: 100px  100px  0 0;} 
        /* border-radius: 50px  圆角 */
    </style>
</head>
<body>
    <div id="box1"></div><br>
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     <div id="box3"></div><br>
     <div id="box4"></div><br>
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</body>
</html>